Processing Technology Of Eastern Zhejiang Featured Pickled Wax Gourd And Changes Of Quality Characteristics

Pickled wax gourd, commonly known as wax gourd with strong odor, which ispopular in eastern Zhejiang as a kind of traditional fermented food. In recent years, as"home cooking","special cooking", the value of wax gourd with strong odor has improvedgreatly. It has unique flavor and can stimulate your appetite, which is loved by the youngand the old. In this paper, the physical and chemical indicators as well as microbiologicalinfluences were investigated, and the sensory evaluation of its product was conductedduring fermentation. The best pickled technology was analyzed and the optimumpreservation conditions were drawn finally. The main study results were as follows.Study on isolation and identification of lactic acid bacteria (LAB) from pickled waxgourd has shown that, the9LAB strains were isolated from the samples of natural pickledwax gourd, the physiological and biochemical characteristics proved that the9LABstrains had high similarity with the ones belonged to2genera and3species. The bacillibelonged to Lactobacillus, and the cocci belonged to pediococcus. Meantime, the16SrRNA gene sequencing was used to identify the isolates, the results proved that lactic acidbacteria from natural pickled wax gourd had Lactobacillus plantarum (Lp), Lactobacillusbrevis (Lb) and Pediococcus pentosaceus (Pp).Quality analysis study of the pickled wax gourd in different processing technologyhas shown that, the picking period of cooked pickling required20days, but it is90daysfor raw pickling. pH of the wax gourd by addition of red pepper was reduced by0.25, andnitrite concentration was reduced by0.86mg kg-1in the raw pickled process as comparingto the control but the total acids increased and salinity changed not significantly. pH of thepickled wax gourd by inoculation pickling was reduced by0.26, and nitrite concentrationwas reduced by13.8mg kg-1than that of the control. The amino nitrogen was increasedby0.017g100g-1, total population of bacteria was increased by3.3×107cfu mL-1andlactic acid bacteria was increased by1.0×107cfu mL-1. By sensory evaluation of fourdifferent processing technology, the quality of products by raw pickling with inoculation or by addition of red pepper was both improved, the best quality of pickling wax gourdwas obtained by inoculating the Pediococcus pertosaceus.The influences of fermented agents on quality changes during the fermentationprocess of pickled wax gourd were investigated, and results showed that, pH of the pickledwax gourd inoculated with seven kinds of fermented agents were significantly lower thanthe control, which was better with the formulation strains of Pp/Lp, total sugar of theinoculated pickled wax gourd in the pickled process declined highly comparing to thecontrol. The content of lactic acid had been increased and had higher levels than thecontrol, especially the pickled wax gourd with the formulation strains of Pp/Lpshowedhigher levels of lactic acid, malic acid and succinic acid were detected in the early stage,but was not detected in the late stage, the content of citric acid was not high at thebeginning of pickling, but increased significantly in the post. Sensory score of pickled waxgourd raw pickling with Pp/Lpwas the highest, Lb/Pp/Lpfollowed, Ppand Lbwere relativelylow. The result showed that inoculating the Pediococcus pentosaceus and Lactobacillusplantarum by the ratio of1:1worked best, the fermentability of Lactobacillus brevis strainis relatively weak. There was an obvious interactivity between different strainformulations．The preservation techniques of pickled wax gourd were also investigated, and theresults showed that, there was no change of acidity under the condition of sterilizationpasteurized and25℃thermostat incubator, but the population of LAB were lower andrelatively stable, the content of nitrite increased in the first and decreased later, hardness,color and flavor went bad; under the condition of4℃temperature storage, acidityincreased and the population of LAB began to decline rapidly, then decline slowly, thecontent of nitrite decreased and hardness was the same, color and flavor scored relativelyhighly; acidity decreased in the first and reduced later under the condition of25℃temperature storage, but the population of LAB were relatively high with the trend of thefirst increasing after decreasing, and the content of nitrite had the trend of the firstincreasing after decreasing, the hardness declined, color and flavor was worse than that ofrefrigeration. The content of nitrite was all lower, which is1.2mg/kg, and the pickles weresafe with these treatment methods above for2months. Above all, the best preservationmethod was the condition of4℃temperature storage.